1. Field of the Invention
This invention relates to a knob, more particularly to a knob for a linear control that can be twisted off a shaft without damage to knob or shaft.
2. Description of the Related Art
Knobs are generally designed to fit onto shafts to facilitate turning the shafts. These shafts generally have round or "D"-shaped cross sections. Often the shaft is an element of a rotary potentiometer.
Knobs may also be used to facilitate linear motion of a shaft which may be an element of a linear slide potentiometer. In that case, the shaft generally has a rectangular cross section and moves parallel to one of the sides of the rectangle. A shaft hole in the knob is generally designed to fit snugly on the shaft. Since knobs for rotary controls are more common, a person who encounters a particular knob for the first time may be inclined to twist it. Twisting a linear-control knob will often cause damage to the knob interior, the shaft, or both.
Knobs for linear controls are available commercially from Rogan Corporation, of Northbrook, Ill., and from other manufacturers. An example of a product that incorporates a knob for linear control is the Skylark.RTM. dimmer, manufactured by Lutron Electronics Corp., of Coopersburg, PA.